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Subject: Re: [std-proposals] Reserve good keywords for floating point types
From: Tony V E (tvaneerd_at_[hidden])
Date: 2019-10-15 10:07:13


On Tue, Oct 15, 2019 at 7:23 AM Lyberta via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> Thiago Macieira via Std-Proposals:
> > They are not broken. Neither int nor double are.
> >
> > If you need specific format or bit-width, then you use the one with that
> in
> > the name. If you don't and you can just live with whatever size the
> compiler
> > wants to give you, use that.
> >
>
> All modern compiled (and some (most?) VM-based) languages give users
> fixed layout because it is important to know so you have understanding
> what is going on.
>
> > Then do what everyone else does and start with floatN and modify it from
> > there. Granted, I know your naming extends from P1468, but that is one
> ugly
> > naming scheme (itself derived from an existing emergent convention in
> > literature that float64's natural extention should be called the
> arbitrary
> > binary128 rather than float128). I have no idea why the word "binary" is
> > used in the name of a float, but the word "float" isn't. Everything is
> > binary. Eh well.
>
> No really. IEEE 754-1985 had "single precision" and "double precision"
> and later versions renamed those to binary32 and binary64 because of
> addition of decimal floating point formats. Float32 and float64 were
> never an official names.
>
> Should "float" be renamed to "single" then?
>
> > And they should. They are more legitimate. The compiler knows best for
> the
> > target machine. When it comes to communication, it's the human's job to
> > coerce it into a different representation. The two are very different
> > scenarios.
>
> Any useful program is connected to the Internet. Maybe by proxy i.e. its
> data is sent over by another program. Knowing exact binary layout is
> crucial.
>
> > std::floatN_iec559_t makes much more sense then.
>
> It doesn't specify if it's binary or decimal.
>
> > No need to be so dramatic. The fundamental types are not broken, they're
> > just flexible. They don't set specifics in stone because every platform
> is
> > different, has different capabilities, efficient storage, access and
> > calculation capabilities. A general purpose language needs that
> flexibility
> > for typical situations but also needs to give the user control over
> > representation when they have a specific reason (though there is most
> > certainly work to be done on *that* front).
>
> Again, flexible types are a relic of the past and only useful in
> extremely rare circumstances. Fixed layout is what's needed in 99% of
> cases.
>

Citation needed.

-- 
Be seeing you,
Tony


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